Congenital fiber type disproportion (CFTD) is a rare congenital myopathy characterized by hypotonia and generalized muscle weakness. Pathologic diagnosis of CFTD is based on the presence of type 1 ...fiber hypotrophy of at least 12% in the absence of other notable pathological findings. Mutations of the ACTA1 and SEPN1 genes have been identified in a small percentage of CFTD cases. The muscle tropomyosin 3 gene, TPM3, is mutated in rare cases of nemaline myopathy that typically exhibit type 1 fiber hypotrophy with nemaline rods, and recently mutations in the TPM3 gene were also found to cause CFTD. We screened the TPM3 gene in patients with a clinical diagnosis of CFTD, nemaline myopathy, and with undefined congenital myopathies. Mutations in TPM3 were identified in 6 out of 13 patients with CFTD, as well as in one case of nemaline myopathy. Review of muscle biopsies from patients with diagnoses of CFTD revealed that patients with a TPM3 mutation all displayed marked disproportion of fiber size, without type 1 fiber predominance. Several mutation-negative cases exhibited other abnormalities, such as central nuclei and central cores. These results support the utility of the CFTD diagnosis in directing the course of genetic testing. Hum Mutat 30:1-8, 2009.
Participating in yoga may be ideal for college students to increase physical activity and improve mental health.
To investigate the feasibility and impact of an 8-week yoga intervention within a ...university setting on mental and physiologic heath.
This 8-week yoga intervention included twelve yoga-naïve adults, (23.8 ± 4.6 years; 71% female). Participants attended two 60-min yoga classes/week in addition to baseline, mid- and post-lab visits.
83% of participants attended ≥75% of yoga classes. Stress and depression symptoms decreased by 11% and 25%, respectively and erythrocyte sedimentation rate (ESR) reduced by 28%. Participants who did not meet physical activity recommendations observed greater improvements in stress, depression symptoms, ESR, and C-reactive protein compared to participants who met recommendations.
The majority of participants attended ≥12 of 16 yoga classes. Exploratory analyses provide preliminary support for the impact of yoga on reducing stress, symptoms of depression, and ESR. Participants who were not meeting physical activity guidelines prior to starting the intervention received greater benefits.
Abstract
Mutations in at least 12 genes are responsible for a group of congenital skeletal muscle diseases known as nemaline myopathies (NMs). NMs are associated with a range of clinical symptoms and ...pathological changes often including the presence of cytoplasmic rod-like structures (nemaline bodies) and myofiber hypotrophy. Our recent work has identified a variable degree of behavioral benefit when treating 2 NM mouse models due to mutations in Acta1 with myostatin inhibition. This study is focused on the effects of delivering ActRIIB-mFc (Acceleron; a myostatin inhibitor) to the nebulin conditional knockout KO (Neb cKO) mouse model of NM. Treatment of Neb cKO mice with ActRIIB-mFc did not produce increases in weight gain, strength, myofiber size, or hypertrophic pathway signaling. Overall, our studies demonstrate a lack of response in Neb cKO mice to myostatin inhibition, which differs from the response observed when treating other NM models.
Loss‐of‐function mutations in the deoxyguanosine kinase (DGUOK) gene result in a mitochondrial DNA (mtDNA) depletion syndrome. DGUOK plays an important role in converting deoxyribonucleosides to ...deoxyribonucleoside monophosphates via the salvage pathway for mtDNA synthesis. DGUOK deficiency manifests predominantly in the liver; the most common cause of death is liver failure within the first year of life and no therapeutic options are currently available. in vitro supplementation with deoxyguanosine or deoxyguanosine monophosphate (dGMP) were reported to rescue mtDNA depletion in DGUOK‐deficient, patient‐derived fibroblasts and myoblasts. CERC‐913, a novel ProTide prodrug of dGMP, was designed to bypass defective DGUOK while improving permeability and stability relative to nucleoside monophosphates. To evaluate CERC‐913 for its ability to rescue mtDNA depletion, we developed a primary hepatocyte culture model using liver tissue from DGUOK‐deficient rats. DGUOK knockout rat hepatocyte cultures exhibit severely reduced mtDNA copy number (~10%) relative to wild type by qPCR and mtDNA content remains stable for up to 8 days in culture. CERC‐913 increased mtDNA content in DGUOK‐deficient hepatocytes up to 2.4‐fold after 4 days of treatment in a dose‐dependent fashion, which was significantly more effective than dGMP at similar concentrations. These early results suggest primary hepatocyte culture is a useful model for the study of mtDNA depletion syndromes and that CERC‐913 treatment can improve mtDNA content in this model.
AAV-based gene therapy is an attractive approach to treat Duchenne muscular dystrophy (DMD) patients. Although the long-term consequences of a gene therapy approach for DMD are unknown, there is ...evidence in both DMD patients and animal models that dystrophin replacement by gene therapy leads to an anti-dystrophin immune response that is likely to limit the long-term use of these therapeutic strategies.
Our objective is to test whether the anti-dystrophin immune response is affected by immunomodulatory drugs in mdx mice after rAAV gene therapy.
mdx mice were treated with rAAV microdystrophin alone or in combination with immunomodulatory drugs. Dystrophin expression in skeletal muscle was assessed by mass spectrometry. Immune responses were assessed by immunophenotyping, western blot for anti-dystrophin antibodies and flow cytometry assays for antigen-specific T-cell cytokine expression. The impact on muscle was measured by grip strength assessment, in vivo torque, optical imaging for inflammation and H&E staining of sections to assess muscle damage.
We found that AAV-9-microdystrophin gene therapy induced expression of microdystrophin, anti-dystrophin antibodies, and T-cell cytokine responses. Immunomodulatory treatments, rituximab and VBP6 completely abrogated the anti-dystrophin antibody response. Prednisolone, CTLA4-Ig, and eplerenone showed variable efficacy in blocking the anti-dystrophin immune response. In contrast, none of the drugs completely abrogated the antigen specific IFN-γ response. AAV-microdystrophin treatment significantly reduced inflammation in both forelimbs and hindlimbs, and the addition of prednisolone and VBP6 further reduced muscle inflammation. Treatment with immunomodulatory drugs, except eplerenone, enhanced the beneficial effects of AAV-microdystrophin therapy in terms of force generation.
Our data suggest that AAV-microdystrophin treatment results in anti-dystrophin antibody and T-cell responses, and immunomodulatory treatments have variable efficacy on these responses.
We tested the hypothesis that voluntary wheel running would complement microdystrophin gene therapy to improve muscle function in young mdx mice, a model of Duchenne muscular dystrophy. mdx mice ...injected with a single dose of AAV9-CK8-microdystrophin or vehicle at age 7 weeks were assigned to three groups: mdxRGT (run, gene therapy), mdxGT (no run, gene therapy), or mdx (no run, no gene therapy). Wild-type (WT) mice were assigned to WTR (run) and WT (no run) groups. WTR and mdxRGT performed voluntary wheel running for 21 weeks; remaining groups were cage active. Robust expression of microdystrophin occurred in heart and limb muscles of treated mice. mdxRGT versus mdxGT mice showed increased microdystrophin in quadriceps but decreased levels in diaphragm. mdx final treadmill fatigue time was depressed compared to all groups, improved in mdxGT, and highest in mdxRGT. Both weekly running distance (km) and final treadmill fatigue time for mdxRGT and WTR were similar. Remarkably, mdxRGT diaphragm power was only rescued to 60% of WT, suggesting a negative impact of running. However, potential changes in fiber type distribution in mdxRGT diaphragms could indicate an adaptation to trade power for endurance. Post-treatment in vivo maximal plantar flexor torque relative to baseline values was greater for mdxGT and mdxRGT versus all other groups. Mitochondrial respiration rates from red quadriceps fibers were significantly improved in mdxGT animals, but the greatest bioenergetic benefit was observed in the mdxRGT group. Additional assessments revealed partial to full functional restoration in mdxGT and mdxRGT muscles relative to WT. These data demonstrate that voluntary wheel running combined with microdystrophin gene therapy in young mdx mice improved whole-body performance, affected muscle function differentially, mitigated energetic deficits, but also revealed some detrimental effects of exercise. With microdystrophin gene therapy currently in clinical trials, these data may help us understand the potential impact of exercise in treated patients.
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We report that voluntary exercise complements microdystrophin gene therapy in the mdx mouse, a model of Duchenne muscular dystrophy (DMD), by increasing running endurance, muscle strength, and energy production. These and other findings may help us understand how exercise in DMD boys may influence microdystrophin gene therapy.
Limb contractures are debilitating complications associated with various muscle and nervous system disorders. This report summarizes presentations at a conference at the Shirley Ryan AbilityLab in ...Chicago, Illinois, on April 19–20, 2018, involving researchers and physicians from diverse disciplines who convened to discuss current clinical and preclinical understanding of contractures in Duchenne muscular dystrophy, stroke, cerebral palsy, and other conditions. Presenters described changes in muscle architecture, activation, extracellular matrix, satellite cells, and muscle fiber sarcomeric structure that accompany or predispose muscles to contracture. Participants identified ongoing and future research directions that may lead to understanding of the intersecting factors that trigger contractures. These include additional studies of changes in muscle, tendon, joint, and neuronal tissues during contracture development with imaging, molecular, and physiologic approaches. Participants identified the requirement for improved biomarkers and outcome measures to identify patients likely to develop contractures and to accurately measure efficacy of treatments currently available and under development.
Nemaline myopathy, the most common non-dystrophic congenital myopathy, is caused by mutations in six genes, all of which encode thin-filament proteins, including NEB (nebulin) and TPM3 (α ...tropomyosin). In contrast to the mechanisms underlying weakness in NEB-based myopathy, which are related to loss of thin-filament functions normally exerted by nebulin, the pathogenesis of muscle weakness in patients with TPM3 mutations remains largely unknown. Here, we tested the hypothesis that the contractile phenotype of TPM3-based myopathy is different from that of NEB-based myopathy and that this phenotype is a direct consequence of the loss of the specific functions normally exerted by tropomyosin. To test this hypothesis, we used a multidisciplinary approach, including muscle fiber mechanics and confocal and electron microscopy to characterize the structural and functional phenotype of muscle fibers from five patients with TPM3-based myopathy and compared this with that of unaffected control subjects. Our findings demonstrate that patients with TPM3-based myopathy display a contractile phenotype that is very distinct from that of patients with NEB-based myopathy. Whereas both show severe myofilament-based muscle weakness, the contractile dysfunction in TPM3-based myopathy is largely explained by changes in cross-bridge cycling kinetics, but not by the dysregulation of sarcomeric thin-filament length that plays a prominent role in NEB-based myopathy. Interestingly, the loss of force-generating capacity in TPM3-based myopathy appears to be compensated by enhanced thin-filament activation. These findings provide a scientific basis for differential therapeutics aimed at restoring contractile performance in patients with TPM3-based versus NEB-based myopathy.
Mutations in ASAH1 have been linked to two allegedly distinct disorders: Farber disease (FD) and spinal muscular atrophy with progressive myoclonic epilepsy (SMA-PME). We have previously reported ...FD-like phenotypes in mice harboring a single amino acid substitution in acid ceramidase (ACDase), P361R, known to be pathogenic in humans (P361R-Farber). Here we describe a mouse model with an SMA-PME-like phenotype (P361R-SMA). P361R-SMA mice live 2-3-times longer than P361R-Farber mice and have different phenotypes including progressive ataxia and bladder dysfunction, which suggests neurological dysfunction. We found profound demyelination, loss of axons, and altered sphingolipid levels in P361R-SMA spinal cords; severe pathology was restricted to the white matter. Our model can serve as a tool to study the pathological effects of ACDase deficiency on the central nervous system and to evaluate potential therapies for SMA-PME.
We have developed an injectable foam suspension containing self-assembling, lipid-based microparticles encapsulating a core of pure oxygen gas for intravenous injection. Prototype suspensions were ...manufactured to contain between 50 and 90 ml of oxygen gas per deciliter of suspension. Particle size was polydisperse, with a mean particle diameter between 2 and 4 μm. When mixed with human blood ex vivo, oxygen transfer from 70 volume % microparticles was complete within 4 s. When the microparticles were infused by intravenous injection into hypoxemic rabbits, arterial saturations increased within seconds to near-normal levels; this was followed by a decrease in oxygen tensions after stopping the infusions. The particles were also infused into rabbits undergoing 15 min of complete tracheal occlusion. Oxygen microparticles significantly decreased the degree of hypoxemia in these rabbits, and the incidence of cardiac arrest and organ injury was reduced compared to controls. The ability to administer oxygen and other gases directly to the bloodstream may represent a technique for short-term rescue of profoundly hypoxemic patients, to selectively augment oxygen delivery to at-risk organs, or for novel diagnostic techniques. Furthermore, the ability to titrate gas infusions rapidly may minimize oxygen-related toxicity.
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